When Josh Reynolds and Maris Ambats introduced their color-changing “mood ring” in American stores in 1975, few could have anticipated just how quickly the novelty jewelry would explode in popularity. By the end of the year, $20 million worth of mood rings had sold.

As one local newspaper reporter wrote of the phenomenon three months after their introduction, “Mood rings are to fingers in 1975 what hula hoops were to hips in the 1950s.”

Parents and teenagers flocked to buy the rings, which contained “thermotropic liquid crystals that changed color based on your body heat to indicate your mood,” explains author Kelly Boyer Sagert, who researched the jewelry fad for her book The 1970s. When the oval-shaped crystal at the center of the ring changed to black it showed that the user was stressed. Yellow signaled that they were unsettled, green meant mixed emotions, while blue was relaxed. 

Days after the $45 silver-plated rings were introduced in New York City at the upscale department store Bonwit Teller, The New York Times ran a story reporting that hundreds of consumers were “storming the jewelry counter” there. That fall, a manager of the Alexander’s department store in Monmouth, New Jersey, described how hard the fad was hitting his suburban shore town, telling the local newspaper they had sold thousands in just three weeks. “We had to send a truck to get more. We’ve ordered about 25,000 of them.” 

A few months later, the popularity of mood rings had already begun to dwindle—as the market was flooded with poor quality knockoffs. In 1977, Reynolds filed for bankruptcy. 

But why did mood rings capture the imagination of the world so intensely? 

Who created the mood ring remains a topic of some debate. A jewelry designer named Marvin Wernick says he invented the mood ring years before 1975, developing the idea after he saw a doctor use thermochromic (temperature-measuring) tape on a patient. 

Reynolds said he came up with the idea of the mood ring after the stresses of working on Wall Street led him to explore biofeedback, a therapeutic technique where people improve their health by responding to signals from their own bodies. “He called himself a self-schooled behavioral scientist,” explains Sagert. “He had gone through a stage of his life where he was basically a hermit. He did various therapies searching for enlightenment.” 

The crystals perfectly suited Reynolds’ behavioral pursuits, as they instantly told people how they were feeling, which he felt would prompt them to change their mood. “He wanted to give people information on their own bodies, which would allow them to mellow out and be more peaceful.” 

Reynolds’ mood ring sales soon started outselling Wernick’s version. (Neither creator bothered to apply for a patent.) Sagert credits the business contacts Reynolds had made while working in the Financial District for this success. It also helped that, according to the PR News Wire, mood rings had a “massive surge of PR [that] swept across the country. 

The 1970s—once dubbed the “Me" decade by author and journalist Tom Wolfe—was a fitting time to launch the mood ring, says Sagert. Pursuits like jogging, yoga, Transcendental Meditation and jazzercise took off during the decade, as the concept of wellness began to enter the cultural discourse. “Everything [in the era] was about analyzing yourself, asking, ‘Who am I? What are my feelings?’," says Sagert. "Mood rings symbolize this era more than anything.” 

Of course, the jewelry didn’t actually inform users how they were feeling. “They just told you what your body temperature was,” says Sagert. “You just had to rub your hands to get warm and be happy. You could manipulate the results.”

This didn’t stop Reynolds and his competitors from creating mood-revealing necklaces, nail polish and even undergarments. But without a patent, the competition was so fierce, and their appeal so fleeting, that mood rings slipped out of public consciousness by 1977.

“The crystals in the rings only lasted for a year or two,” recalls Sagert. “By the time everyone's mood rings stopped working, the fad was over.” Nostalgia merchants pushed a brief mood ring revival in the 1990s, and they’re still available today in a variety of new designs. But for Sagert, mood rings will always be “one of those fads” where “everyone went insane for them, they died away and then no one ever talked about them again.”